Source/Drain Epitaxial Cleaning Sequence for Defect Uniformity
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Solution Overview
Problem
The scaling down of semiconductor devices has introduced short-channel effects and epitaxial defects in FET devices, leading to reduced off-state current and device performance, due to residual gases and non-uniformity in source/drain epitaxial structures, which complicates the manufacturing process and decreases yield.
Innovation Solution
Implementing optimized cleaning processes, including elevated temperature chamber cleaning, hydrogen environment baking, and etching gas flushes with lower flow rates and shorter times to reduce residual gases and defects, followed by a pumping process to further minimize epitaxial defects, resulting in more uniform S/D epitaxial structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning processes are used, then process time is reduced, but epitaxial defects increase due to residual gases
Solution Approach 1:
The patent applies preliminary action by performing elevated temperature chamber cleaning and hydrogen environment baking before the epitaxial growth process. This pre-treatment removes residual gases and contaminants from the chamber and substrate, preventing epitaxial defects from forming during subsequent growth, thereby improving reliability without requiring extended processing time during the actual epitaxial formation.
Solution Approach 2:
The patent changes physical parameters by implementing elevated temperature cleaning (increasing temperature parameter) and using hydrogen environment baking. These parameter changes enable more effective removal of residual gases and contaminants, reducing epitaxial defects. The optimized etching gas flushes with lower flow rates and shorter times also represent parameter optimization to balance cleaning effectiveness with process time.
2Productivity
If scaling down is continued to increase storage capacity and performance, then device dimensions are reduced, but short-channel effects and epitaxial defects increase
Solution Approach 1:
The patent applies preliminary action by performing elevated temperature chamber cleaning and hydrogen environment baking before the epitaxial growth process. This pre-treatment removes residual gases and contaminants from the chamber and substrate, preventing epitaxial defects from forming during subsequent growth, thereby improving reliability without requiring extended processing time during the actual epitaxial formation.
Solution Approach 2:
The patent changes physical parameters by implementing elevated temperature cleaning (increasing temperature parameter) and using hydrogen environment baking. These parameter changes enable more effective removal of residual gases and contaminants, reducing epitaxial defects. The optimized etching gas flushes with lower flow rates and shorter times also represent parameter optimization to balance cleaning effectiveness with process time.
3Manufacturing precision
If optimized cleaning processes are implemented, then epitaxial defects are reduced and profile uniformity is improved, but process complexity increases
Solution Approach 1:
The patent merges multiple cleaning functions into a integrated sequence: elevated temperature chamber cleaning, hydrogen environment baking, and optimized etching gas flushes are combined into a coordinated process flow. This integration achieves comprehensive contaminant removal and profile uniformity improvement while managing process complexity through systematic organization of the cleaning steps rather than treating them as separate, independent operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces epitaxial defects, improves profile uniformity of S/D epitaxial structures, and increases process yield by 5% to 20%, achieving better device performance and reduced dimension variations.
Implementation Method 1
cleaning the chamber with a first etching gas
Implementation Method 2
cleaning the substrate and the chamber with a flush of a second etching gas different from the first etching gas
Implementation Method 3
etching a portion of the first epitaxial layer with a third etching gas
Implementation Method 4
baking the wafer and the epitaxial growth chamber in a hydrogen environment
Implementation Method 5
depositing the first epitaxial layer on the substrate in the chamber
Implementation Method 6
epitaxially growing a first portion of the first epitaxial layer with a precursor
Data Source
AI summary
The present disclosure describes a method of forming an epitaxial layer on a substrate in a chamber. The method includes cleaning the chamber with a first etching gas and depositing the epitaxial layer on the substrate. Deposition of the epitaxial layer includes epitaxially growing a first portion of the epitaxial layer with a precursor, cleaning the substrate and the chamber with a flush of a second etching gas different from the first etching gas, and epitaxially growing a second portion of the epitaxial layer with the precursor. The first portion and the second portion have the same composition. The method furthers includes etching a portion of the epitaxial layer with a third etching gas having a flow rate higher than that of the second etching gas.